At “Game of Thrones” viewing parties in San Francisco, fans rewatched Dothraki scenes to study the language in a workshop-like setting. Last October, a group of Na’vi speakers from half a dozen countries convened in Sonoma County, Calif., for a gathering known as “Teach the Teachers.” Mr. Frommer gave attendants tips on grammar and vocabulary and fielded any questions they had about the language. The rural, wooded setting felt “almost like being on Pandora,” he said. At a question-and-answer session in July that he participated in, at least a dozen attendants rattled off their questions in fluent Na’vi.

I will never be this big a fan of anything.